Inclusion of Height and Limb Length when Interpreting Sympathetic Skin Response

It is more than a decade since scientists are making use of sympathetic skin response (SSR) as a clinical and research method to evaluate sympathetic nervous system. A major portion of the efferent pathway of this response is composed of non-myelinated nerves. Thus, the latency of the response may be significantly different in normal individuals with different height and limb lengths. This study was designed to investigate the effect of these parameters on the SSR results. We measured the height and limb length of 65 normal individuals with different heights (divided into 3 groups of height ≤150 cm, 150-170 cm, and ≥170 cm). The participants had neither peripheral nor central neuropathy. They also had none of the exclusion criteria. Then, they underwent SSR testing of both palms and soles. The correlation between the height and limb length in relation to SSR parameters (latency and amplitude) was analyzed statistically by Pearson's correlation. No significant correlation was detected between the height and limb length and the SSR amplitude. However, the results showed significant correlation between SSR latency recorded from all four sites (both palms and soles) and the height of participants. Furthermore, there was a significant correlation between SSR latency recorded from any limb and the length of that limb. Regarding the significant effect of the height and limb length on the SSR latency, both the height and limb length should be considered when interpreting the results of SSR.